What 145 owners told NHTSA about the 2021 GMC Acadia Denali

VEHICLE'S ENGINE INCURRED COOLANT TEMPERATURE ISSUES, SET DTC CODE, AND COOLING FAN RAN AFTER ENGINE WAS TURNED OFF. DEALER DIAGNOSED AS THERMOSTAT FAILURE AND COMPLETED REPAIRS. DEALER CHECKED AND FOUND NO SERVICE ASSISTANCE FOR REPAIR EVEN THOUGH THERE WAS A BACK ORDER FOR REPLACEMENT PARTS AND WAS SECURED THROUGH DEALER IN DETROIT CURRENT NHTSA ID NUMBER 110243390 / MFG COMMUNICATION # N252508350 REFERRING TO 3.6 V-6 ENGINE. GMC DECLINED ANY MONETARY ASSISTANCE TOWARDS REPAIRS WITH 76278 MILES I ALSO OWN A 2020 CHEVROLET BLAZER WITH A 3.6 V-6 ENGINE THAT EXPERIENCED SAME FAILURE PAID $400 DEDUCTABLE TOWARD REPAIR

NHTSA ODI 11701422

The infotainment center/and On Star alert systems ( crash detections / SOS ) No access to anything in the infotainments center along with most of the safety setting not alerting due to and over the air update failure. yes is available for inspection upon request. all On star safety features are not working if a crash were to happen i would not be able to get help if i was injured. Yes and it is ongoing. BY a GMC certified dealer. No.

NHTSA ODI 11701600

For the 3rd time of ownership the cooling fan stays on after vehicle is turned off and the display “steering assist is reduced, drive with caution”.

NHTSA ODI 11701173

"STEERING ASSIST REDUCED. DRIVE WITH CARE" message, fan runs nonstop, even after the vehicle is off. Sounds like a plane taking off. This seems to be EXTREMELY common after doing my research. Please consider turning this into a recall!

NHTSA ODI 11701250

Getting a pop up that says “steering assist reduced”. Temp gauge drops completely. AC won’t work and fan kicks on

NHTSA ODI 11701260

The thermostat failed which cause the steering system to fail and car to not read temperature

NHTSA ODI 11701121

The contact owns a 2021 GMC Acadia. The contact stated that while his wife was driving at an undisclosed speed, the vehicle inadvertently lost motive power. The driver was able to coast to the shoulder of the roadway, where the vehicle failed to restart. The check engine warning light was illuminated. The vehicle was towed to an independent mechanic, who diagnosed a failure with the fuel pump control module. The vehicle was repaired. The manufacturer was notified of the failure but provided no assistance. The failure mileage was 36,970.

NHTSA ODI 11700332

GM need to be looked at for faulty Thermostats being put into vehicles. While driving the message "steering assist is reduced " You get to a safe place and shut you car off and the fan still runs. After speaking with my dealer today, he said he has done 7 in last week. And if you look online, everyone especially Acadia models is having this problem. Customers are getting charged alot of money for the repair. To me this is a defective thermostat on GM and needs to be addressed

NHTSA ODI 11699969

ABS Modulator failed leaking oil. Loss of braking Repair service found the same problem. Part was scrapped.

NHTSA ODI 11699678

Often times, on the heads-up display I would get "Steering Assist is Reduced Drive with Care" and my temp gauge will stop working and when I stop, my fan continues to run until I disconnect the battery for 20 secs.

NHTSA ODI 11699159

The contact owns a 2021 GMC Acadia. The contact stated while driving 75 MPH, the check engine warning light illuminated. Additionally, the accelerator pedal was depressed, but the vehicle failed to accelerate as intended. The vehicle was driven to the shoulder of the road. The contact stated while attempting to start the vehicle, the vehicle failed to start as intended. The contact stated that the failure had nearly caused the vehicle to be run over by a tractor trailer. The contact's wife and three minor children were also occupying the vehicle during the failure. The contact stated that he and his family could have been killed due to the failure. The vehicle was towed to the dealer, where it was diagnosed with fuel pump power control module failure. The contact was informed that the fuel pump power control module needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was filed. The contact related the failure to an unknown recall; however, the VIN was not included in the recall. The failure mileage was approximately 35,500.

NHTSA ODI 11698177

Transmission feels like it’s slipping, almost like a jerky shift from any stop, seems like a common issue and should be recalled!

NHTSA ODI 11698037

I was driving home and about 10 minutes into my drive I got a notification about my steering assistance being disabled. When I arrived home about 10 minutes or so later and went to shut my car off I noticed that a very loud fan sound from the hood of my vehicle began roaring. I restarted my car and it went away. I looked at my temperature gauge and it was all the way on C. I tried shutting my car off again and the loud electrical fan sound picked right back up again. I stayed in my vehicle while it was turned off waiting to see if it would stop while trying to call for answers. I couldn’t risk having a dead battery for work tomorrow morning. After what was about 6-7 minutes the electrical fan finally shut off. Turns out my aunt JUST had this exact same issue with her 2021 GMC Acadia as well. According to Reddit MANY people are having this issue yet there is still no recall for this problem. My car is only at 85K miles, has always been dealership maintained and has never had any issues like this until now. If this is a wide spread make and model issue a recall should have been issued.

NHTSA ODI 11697020

Recently took vehicle for alignment for a pull to the right. After 3 alignments at the dealership I was told the rack and pinion gear sensor shorted out causing the vehicle to pull to the right. Also the exhaust has a rattle in the resonator confirmed by 2 sources. I asked the dealer to fix years ago under bumper to bumper and tsb PIT5863. I was told not enough techs and not enough time so now the warranty is expired and the issue isn't fixed.

NHTSA ODI 11696423

While driving, error popped up stating steering assist is reduced; drive with caution. Heat was no longer working. Engine temp was reading cold even though vehicle had been running for half hour and temp outside was 65 F. After vehicle was stopped, engine fan ran very loudly for at least 15 minutes. Took vehicle in to have diagnostics ran, and received error P0128 pointing to faulty engine coolant thermostat and sensor. Also received U0401 indicating insufficient data coming from ECM/PCM. I was told that together with U0401 and P0128 together indicate a communication problem between control modules. Check engine light was never on.

NHTSA ODI 11694926

*Transmission or torque converter. *Vehicle shuddering or shaking at low speeds or when shifting. *Studders while trying to drive fromstop. Can casue accident. *No check engine lights or any warnings prior to failure. *Did not accuse anything when checked by diagnostice tool. *Issue started in Sept but is ongoing

NHTSA ODI 11692057

Received message "Steering assist is reduced. Drive with care". This is related to a faulty thermostat and temperature sensor.

NHTSA ODI 11688963

I have a 2021 GMC Acadia that keeps saying steering assist not available. But when it does this, the temperature gage stops working and so does the AC. After you turn the car off the fan still runs for at least 10 minutes.

NHTSA ODI 11688739

This is a well known issue. On the dash it keeps reading steering system is being reduced drive with care. I have been dealing with this issue almost years. Been to the dealership too many times for this issue

NHTSA ODI 11685299

My Acadia, 2021 has just 36011 miles. Car sputtered a few times like it was running out of gas and stalled as I was driving home in rush hour traffic. I couldn't even get it off the road. No warning lights or advance warning. Waited 3 hours for AAA (told 20 minutes) and then towed to dealer. Tow person could not get it into neutral so they used the sleds to ramp it up onto the flatbed. The dealer replaced the fuel module board which seems to be a common problem with these cars. Dangerous in that I thought someone might rear end the car while sitting in the single lane. Look on the Acadia forum and you'll see this is common and no recall has been issued and it sounds like it could very well happen again.

NHTSA ODI 11682800

I was driving down a heavy traffic expressway with a lot of semi traffic and the SUV started puttering. All of a sudden it died, the check engine light came on and I started to slow down quickly. I was in the middle lane of 3 lanes going 70 mph. VERY LUCKILY, I was able to pull to the right and barely made it onto the shoulder. The SUV had $28,972 miles on it. It was more that 100 degrees outside at the time. I called for a tow and had to wait over 2 hours. My car was nearly hit many times during the wait. The whole situation was very dangerous. What if my children were in the car at the time???? The tow truck driver was nearly killed while trying to get it on the truck. He had to call the police to block the lane. He stated that he could not put it in neutral and had to do something else with it to get it up. It was towed to the dealership where I purchased it. They did the diagnostics and said it was a fuel pump module issue. Less than 30,000 miles and this happened. I was planning to take a trip through the mountains, but at this point I do not feel safe at all in this vehicle. THIS SHOULD BE A RECALL IF GMC IS AWARE OF THIS ISSUE!!!!!

NHTSA ODI 11682193

Instrument cluster malfunction. Entire instrument cluster blacking out every 60 seconds, then rebooting nonstop while driving. While this was occurring, none of the advanced driver assistance systems functioned, nor did the speedometer or other gauges. This occurred while on a trip, and meant having to travel a long distance without having emergency braking, collision warnings or the ability to monitor speed. The car was taken to local dealer and they replaced the entire instrument cluster.

NHTSA ODI 11679159

Car was parked overnight in my garage and in the morning it would turn over, but not start. Had to have it towed to my GMC dealer, but had great difficulty moving the car out of the garage because the transmission remains in PARK if the engine is not running. Had this happened on a highway while driving and without a place to safely get off the road ( which HAS happened to others who have made this same complaint to NHTSA), this could have been an extremely hazardous situation for the occupants of the vehicle. The engine will suddenly shut down, power steering is lost, and power braking will also be lost. This problem was diagnosed as a failed fuel pump module. The failed part was replaced by the dealer (GM part#13554820). The service manager acknowledged that this is a known and common issue and that GM is aware of it but has not issued a voluntary recall. The manager also advised that this part has not been updated and that it may fail again without warning. Please....this is a serious safety issue that needs to be addressed before someone is injured or killed while abandoning a car stalled in traffic that cannot be moved.

NHTSA ODI 11679168

The fuel pump control module failed, 2021Acadia Denali First time, 9/22/21 8073 miles, the car was parked at the residence under the car port, when needed, the car would not start. No check engine or other indicators. Car was towed to dealer for repairs under warranty. Second time, 10/6/23 31879 miles, we were driving the car on a rural road, 55 mph speed limit with no shoulders when the car stopped in a curve. Had to flag down cars to keep them from hitting us for an hour till the wrecker loader it on the truck to take back to same dealership for warranty repairs. Third time, 7/29/25 48199 miles, we were again on a rural road 55 mph speed limit when the car stopped with my 71 year old wife alone in the car, again in a curve. This time there was a check engine light. I drove my truck to pick her up and assist her until the wrecker came. This time with luck I was able to restart the car and I followed her to our home where the tow truck picked it up and brought it to the same dealership for the third time for repairs under warranty. All three times the culprit was the fuel pump control module. Each time it was the same code in the ECM. Each time the dealership said they did a full check on the fuel system, pump, etc. and only replaced the fuel pump control module.

NHTSA ODI 11678212

Driving out of state. My 2021 Acadia with 41,172 miles. When pushing the gas to go there is slippage when trying to accelerate. MY car went automatically into neutral saying transmission and then not start. After a rest period it would start then repeat the same issue. In bumper to bumper traffic on I75. The most Terrifying & UNSAFE place to be at 75 to 80 mph. We happened to be driving up on construction and slow down traffic. When the car stalled. Towed it to a transmission place because of code. They replaced the DTR1 PCM.

NHTSA ODI 11671334